AJP - Cell Physiology, Vol 256, Issue 2 C273-C281, Copyright © 1989 by American Physiological Society

ARTICLES

Effects of general anesthetics on current flow across membranes in guinea pig myocytes

E. Niggli, A. Rudisuli, P. Maurer and R. Weingart
Department of Physiology, University of Berne, Switzerland.

Myocytes were isolated from adult guinea pig ventricles. Whole cell, tight-seal recording was employed to investigate the electrical properties of the junctional (nexal membrane) and nonjunctional membrane (sarcolemma) under the influence of n-alkanols (heptanol, octanol) and halothane. Studies of cell pairs with a double voltage-clamp approach showed that these agents give rise to a reversible electrical uncoupling. Examination of single myocytes with a single voltage-clamp method showed that these substances modify several sarcolemmal current systems. The slope conductance was reduced over the entire voltage range examined (-90 to +50 mV). The Ca2+ inward current (Isi) showed a decreased amplitude and an accelerated inactivation. The repriming of Isi remained unchanged. The steady-state inactivation of Isi was shifted by 2-3 mV toward more negative potentials. Optical measurements demonstrated an increase in sarcomere spacing at rest and a decrease during peak systolic shortening. The results suggest that n-alkanols and halothane exert their effects on membrane currents via incorporation into the lipid bilayer.

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